Preheating of air supplied to the furnaces of water-tube boilers



April s 1924.

H. E. YARROW -PRE`5HEATING OF AIR SUPPLIED TO THE FURNACES OF WATER TUBEBOILERS Filed April 6, 1920 3 Sheets-Sheet 2 April 8 1924.

VH. E. YARRQW PREHEATING oF Ainsuppm'n To 'um FuRNAcEs oF WATER T UBEBomans s sheets-sheet .Filed April 6 agrava Z'yczrr ow A @ma bfowe.

' tral longitudinal plane of the boiler.

Patented Apr. 8, i924.

TED- STATES` PATENT OFFICE.

HAROLD E. YARROW, OF GLASGOW, SCOTLAND.

PREHEATIN G OF AIR SUPPLIED T0 THE FUR-NACE?, 0F WATER-TUBE BOILERS.

Application filed April 6,

To all whom t may concern.' l

Be it known' that I, HAROLD EDGARYAR now, a subject of the King of GreatBritain, residing` in Glasgow, Scotland, have invented certain new anduseful Improvements Relating to theIJreheating of Air Supplied to theFurnaces of VVater-Tube Boilers, of which the following is aspecilication.

The invention relates to means for preheating the air supplied to thefurnaces of water tube boilers by means of the furnace gases, andconsists in an improved disposition of the heating device and of thear-Y rangements by which the air is led to and from the heater'.

According to the invention the heaters are placed in the upper part ofthe boiler casing closely adjacent to the uptake and preferably two setsof heaters are provided symmetrically placed on either side of a 'clenhetubes are arranged horizontally and preferably at right angles to theaxis of the steam and water drum. Cold air is drawn in by fans to theheaters through pockets preferably extending across the central part ofthe left and right side of the boilers; it then passes to compartmentsprovided at the ends of the boiler and is led thence by passages abovethe heaters to the inner ends of the latter and after flowing pasthorizontal tubes disposed at right angles to the steam drum and heatedby the furnace gases, is led into a pocket extending across the boiler'and thence to vertical partitioned spaces at the ends of the boiler andfinally to trunks leading tothe furnaces.

Also, preferably other portions of cold air are drawn throughcompartments at the sides of the boiler and are led between inner andouter casings of the boiler to the passages above the heaters.

In the accompanying drawing which represents an example of thearrangement of air heaters according to the invention, Fig. l is a sideelevation of a water tubeboiler and Figs. 2 and 3 are, respectively,sections on the lines 2-2 and 3-8 of Fig. 1 looking in the direction ofthe arrows.

A is the steam and water drum, B', B2 superheaters placed respectivelybetween two sets of water drums C', C2 and D', D2. rIhe furnace gases,after traversing the 1920. Serial Nlo. 371,749.

water and superheater tubes and dampers E', E2Kenter the tubes f' f2 ofthe air heaters F', F2, whence they pass to the uptake G. Cold air isdrawn into pockets H1 and H2 at the sides of the boiler by mechanicallydriven fans it or by an induced draft fan in the main funnel and is ledthence into vertical compartments I', I2, Is and I4 at the ends of theboiler; these compartments are enclosed by vertical division plates K',K2, K3 and K4 provided at each end of the boiler. Division plates L',L2, L3, and L4 inclined towards the centre of the boiler and extendingto the inner ends of the heaters F', F2 cause the cold air to pass intopassages J, J2 above the heaters and to enter the heaters at the innerends, whence after traversing past baffles M', M2, it emerges intotriangular shaped pockets N', N2. From these pockets the heated airpasses to partitioned compartments O', O2 between the compartments I',I2, I3 and I2 and thence is led by suitable trunks to the fur-` nacesindicated by the bars R.

Also, air flowing between the inner and outer casings of the boiler atQ', Q2 is led into the passages J', J 2 and enters the heaters with theair the course of which is described above.

The path of the cold air is shown by plain and of the heated air byfeathered arrows.

The arrangement of the air heater is obviously not limited. to the caseshown in Y which the superheatersare placed between two water drums; thearrangement according to the invention can be conveniently used wherethe superheaters are diierently placed or in other dispositions adaptedfor water tube boilers.

Having thus described the nature of the said invention andthe best meansI know of carrying the same into practical effect, I claim 1. A watertube boiler, water and also steam and water drums and furnace'therein,pockets extending parallel to said drums along the sides of the boiler,means for inducing a flow of air into said pockets, coinpartments at theends of the boiler into which the air from said pockets flows, an uptakeand boxes closely adjacent thereto, tubes in said boxes heated by theproducts of combustion, past which tubes the air from said compartmentsflows, pockets extending parallel to said drum along the sides of theboiler into which pockets the heated air passes from said boxes,compartments arranged by the side of the Erst mentioned compartmentsseparated therefrom by vertical division plates and receiving the heatedair from said last mentioned pockets,

` and passages leading rom said last nientioned compartments to thefurnaces.

2. A Water tube boiler, Water and also steam and Water drums and furnacetherein, pockets extending parallel to said drums along the sides of theboiler, means for inducing a. flow of air into said pockets,compartments at Vthe ends of the boiler into which the air from saidpockets Hows, an uptake and boxes closely adjacent thereto, tubes insaid boxes heated by the products oi combustion, past which tubes theair from said compartments flows, divison plates in said boxes inclinedtowards the center of the boiler and extending to the inner ends of saidboxes.

3. A Water tube boiler, Water and also steam and Water drums and furnacetherein, pockets extending parallel to said drums along the sides o1"the boiler, means for inducing a flow of air into said pockets,compartments at the ends of the boiler into which the air from saidpockets Hows, an uptake and boxes closely adjacent thereto, tubes insaid boxes heated by the products of combustion, past which tubes theair 'from said compartments flows, an inner and outer casing at theupper part of the boiler, between which casings cold air is drawn in andled to the heating boxes Where it is heated and mixes with the air drawnin from said pockets.

In testimony whereof I have signed my name to this specification.

HAROLD E. YARROV.

